Method of Wetting Evaporative Cooler Media Through a Fabric Distribution Layer

ABSTRACT

An evaporative cooler, and associated method, that includes an evaporative pad including a liquid coolant-receiving surface at which a liquid coolant distributed to the evaporative pad is received and thereafter passes into the evaporative pad. The evaporative cooler also includes a liquid coolant distribution trough that includes an upper portion configured to hold liquid coolant and a lower portion contiguous with the upper portion. The lower portion includes an opening and a fabric distribution layer in place over the opening through which the liquid coolant held in the upper portion of the liquid coolant distribution trough passes and is distributed to the liquid coolant-receiving surface of the evaporative pad.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation-in-part of U.S. patent application Ser. No. 13/173,072, filed Jun. 30, 2011, the entire teachings and disclosure of which are incorporated herein by reference thereto.

FIELD OF THE INVENTION

The present invention relates generally to a method and apparatus concerning the operation of evaporative cooling systems and, in particular, to a method and apparatus concerning the effective wetting by a liquid coolant of an evaporative pad of an evaporative cooling system that cools air supplied to a gas turbine system.

DISCUSSION OF THE PRIOR ART

Evaporative cooling systems, or evaporative coolers as such systems are typically referred to, are employed in various ways in residential, commercial and industrial contexts. In one example, the evaporative coolers cool air that is directed through the evaporative coolers. The evaporative coolers cool the air through the evaporation of a liquid coolant, typically water, which is brought into contact with the air at the evaporative coolers.

Typically, an evaporative cooler includes an evaporative pad at which the air directed to the evaporative cooler is cooled. A liquid coolant, such as water for example, is caused to flow through the evaporative pad and air is brought into contact with the coolant at the pad, usually by means of a fan, blower or turbine drawing or forcing the air through the pad. The evaporative pad typically is constructed of a material that has a large surface area over which the coolant is dispersed so that the coolant assumes a large surface area at the evaporative pad, thereby facilitating the evaporation of the coolant at the pad. Heat transfer takes place between the air and the dispersed coolant, as the air comes into contact with the coolant at the evaporative pad, and the coolant thereby evaporated, causing the air to cool and the density of the air to increase. Coolant is continuously delivered to the evaporative pad to replace the coolant that evaporates.

Evaporative coolers are known to be employed for the purpose of cooling the living spaces of residential structures and the working environments of commercial and industrial buildings for thermal comfort for example. In addition, evaporative coolers are known to be applied in industrial processes in which a supply of cooler and denser air can be used to advantage. For example, an evaporative cooler can be employed in conjunction with a gas turbine system wherein the cooled air from the evaporative cooler is compressed and the compressed air mixed with a fuel such as natural gas for example. The mixture of air and fuel is combusted and the resulting expanding gases are directed to a turbine so as to drive the turbine that, in turn, drives an electrical generator for producing electrical power for example. The cooled air, because of its increased density, provides a higher mass flow rate and pressure ratio at the gas turbine equipment, resulting in an increase in turbine output and efficiency.

The foregoing benefit, however, may not be fully realized in those instances in which the evaporative pad is not completely wetted by the coolant so that the air passing through the pad is cooled to a lesser extent than would be the case in which the pad is entirely wetted by the coolant. Specifically, in previous designs, conduit pipes that drip or spray coolant provide uneven distribution of coolant. Additionally, the areas of the evaporative pad that are not wetted by the coolant can result in the establishment of temperatures in the air that passes through these non-wetted areas that are warmer than the temperatures in the air that has come into contact with the coolant in areas of the evaporative pad that have been wetted by the liquid coolant. These temperature differences in the respective air masses that are then directed to the turbine compressor can cause air turbulence that can result in damage to the turbine equipment. Even in the absence such damage, the vibration of the turbine blades can result in the deteriorated performance of the turbine equipment.

BRIEF DESCRIPTION OF THE INVENTION

The following sets forth a simplified summary of examples of the present invention for the purpose of providing a basic understanding of selected aspects of the invention. The summary does not constitute an extensive overview of all the aspects or embodiments of the invention. Neither is the summary intended to identify critical aspects or delineate the scope of the invention. The sole purpose of the summary is to present selected aspects of the invention in a simplified form as an introduction to the more detailed description of the embodiments of the invention that follows the summary.

In accordance with one aspect, the present invention provides an evaporative cooler that includes an evaporative pad. The evaporative pad includes a liquid coolant-receiving surface at which a liquid coolant distributed to the evaporative pad is received and thereafter passes into the evaporative pad. The evaporative cooler includes a liquid coolant delivery member located above the evaporative pad for delivering the liquid coolant to a location above the evaporative pad. The evaporative cooler includes a liquid coolant distribution trough for receiving the liquid coolant that is delivered to the location above the evaporative pad and for distributing the liquid coolant to the liquid coolant-receiving surface of the evaporative pad. The liquid coolant distribution trough includes an upper portion for receiving the liquid coolant and temporarily holding the liquid coolant and a lower portion contiguous with the upper portion. The lower portion includes an opening directed to the liquid coolant-receiving surface of the evaporative pad and sized congruently with a size of the liquid coolant-receiving surface of the evaporative pad. The lower portion includes a fabric distribution layerbed in place over the opening through which the liquid coolant temporarily held in the upper portion of the liquid coolant distribution trough passes and is distributed to the liquid coolant-receiving surface of the evaporative pad. The liquid coolant temporarily held in the upper portion of the liquid coolant distribution trough wetting an entirety of the fabric distribution layer and the liquid coolant passing through the fabric distribution layer wetting an entirety of the liquid coolant-receiving surface of the evaporative pad.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of the present invention will be apparent to those skilled in the art to which the present invention relates from the detailed descriptions of examples of aspects and embodiments of the invention that follow with reference to the accompanying drawings, wherein the same reference numerals are used in the several figures to refer to the same parts or elements and in which:

FIG. 1 is a schematic side elevational view of an example of an evaporative cooling system, or evaporative cooler, incorporated in an air-conditioning system that supplies cooled air to a gas turbine system;

FIG. 2 is a schematic perspective view of an example of a liquid coolant distribution trough for distributing liquid coolant to an evaporative pad of an evaporative cooler such as the evaporative cooler referred to with respect to FIG. 1;

FIG. 3 is a schematic cross-sectional view of the liquid coolant distribution trough of FIG. 2, with the liquid coolant shown within the trough above a fabric distribution layer;

FIG. 4 is a view similar to FIG. 3, but shows another example fabric distribution layer; and

FIG. 5 is view similar to FIG. 3, but shows yet another example fabric distribution layer.

DETAILED DESCRIPTION OF THE INVENTION

Examples of embodiments that incorporate one or more aspects of the present invention are described below with references, in certain respects, to the accompanying drawings. These examples are not intended to be limitations on the present invention. Thus, for example, in some instances, one or more examples of the present invention described with reference to one aspect or embodiment can be utilized in other aspects and embodiments. In addition, certain terminology is used herein for convenience only and is not to be taken as limiting the present invention.

FIG. 1 schematically illustrates an example embodiment of the invention wherein an evaporative cooling system, or evaporative cooler, indicated generally at 10, is included as a component of an air-conditioning system, indicated generally at 40. The air-conditioning system, including the evaporative cooler 10, is operably associated with a gas turbine system.

A compressor 52 at the gas turbine system 50 functions to draw ambient air into the air inlet 41 of the air-conditioning system 40 and through the air-conditioning system. After being suitably conditioned at the air-conditioning system 40, the air streams through the adapter duct 44 (sometimes referred to as a transition duct or bellmouth) to the compressor 52. The conditioned air, upon entering the compressor 52, is compressed to relatively high pressures. Thereafter, the compressed air enters a combustion area 54 where the compressed air is mixed with a fuel such as natural gas, for example, and the mixture is burned to produce high-pressure, high-velocity gases that are the product of the combustion that takes place in the combustion area 54. The high-pressure, high-velocity gases proceed to a turbine 55 possessed with considerable energy and drive the blades of the turbine that are attached to an output shaft 56. The rotation of the turbine blades causes the output shaft 56 which is attached to rotate as well, and the energy of the output shaft 56 as it rotates is delivered to a generator 58 and electrical energy thereby produced at the generator as will be understood by those having ordinary skill in the art. The use of gas turbine systems is not limited to electrical power generation, however, and the turbine systems also can be applied, for example, to driving pumps and compressors.

For optimum plant operation, air from the ambient environment is used at the gas turbine system 50. The ambient air may first be conditioned and that is accomplished at the air-conditioning system 40. Again referring to FIG. 1, as noted above, ambient air, under the influence of the compressor 52, is drawn into the air-conditioning system at air inlet 41. The ambient air first enters a filter chamber 42 where particulate matter, including in some cases water droplets, is removed from the ambient air. Thereafter, the filtered air passes through the evaporative cooler 10, the operation of which is discussed in greater detail below. However, it is noted here that the evaporative cooler functions to cool the filtered air and increases its density; and, as noted above, the denser air provides a higher mass flow rate and pressure ratio at the gas turbine system 50, resulting in an increase in turbine output and efficiency.

The filtered and cooled air that exits the evaporative cooler 10 flows to demisters 43 which remove unwanted water from the air. From the demisters, the air flows into the adapter duct 44 and from the adapter duct the conditioned air flows to the gas turbine system 50 where the conditioned air after being compressed is mixed with fuel and burned as described above. The arrows in FIG. 1 are all indicative of the flow of the air from its entry into the air-conditioning system 40 at the air inlet 41 to the delivery of the air at the compressor 52 of the gas turbine system 50.

The evaporative cooler 10 itself includes an evaporative pad, indicated generally at 12 in FIG. 2, that includes an air-entry surface 14 at which air delivered to the evaporative pad from the filter chamber 42 enters and passes through the evaporative pad. The evaporative pad 12 also includes an air-exiting surface 16 at which air passing through the evaporative pad, and cooled at the pad, exits from the evaporative pad. The evaporative pad 12 further includes a liquid coolant-receiving surface 18 at which a liquid coolant (e.g., cooling liquid) distributed to the evaporator pad is received and thereafter passes into the evaporative pad. Although various types of liquid coolants can be employed with evaporative coolers, in the example illustrated in the drawings water, either treated or untreated, or in an aqueous solution can be used as the liquid coolant. Untreated water can include raw water taken from the environment or water that has been treated only for the purpose of making it potable. Treated water would include water that has been treated in order to render it more suitable for application to evaporative coolers. Water that has been demineralized and/or treated with surfactants and/or fungicides and bactericides are examples of treated water. Aqueous solutions would include homogeneous mixtures in which water is the solvent.

A reservoir 20 is provided at the air-conditioning unit adjacent the bottom of the evaporative pad 12 as an adjunct to the evaporative cooler 10. Liquid coolant (e.g., water) 27 (shown in FIG. 3) is added to the reservoir 20 (FIG. 1) through liquid inlet 21 in order to maintain sufficient liquid coolant in the reservoir for the purpose of delivering the liquid in adequate amounts to the liquid coolant-receiving surface 18 of the evaporator pad. The delivery of the liquid coolant is accomplished, for example, by means of a pump 24 that pumps liquid from the reservoir 20 through a conduit 25 to a liquid-delivery header 26, which is an example of a liquid coolant delivery member for delivering liquid coolant to a location above the evaporative pad 12. The liquid-delivery header 26 delivers liquid coolant 27 (shown in FIG. 3) to a liquid coolant distribution trough 28 (see FIGS. 1-3) that temporarily retains a volume of the liquid coolant, and, from the trough, the liquid coolant flows to the liquid coolant-receiving surface 18 of the evaporative pad 12. The liquid-delivery header 26 can be configured so as to deliver the liquid coolant 27 in relatively equal amounts along the length (L, see FIG. 2) and across the width (W, see FIG. 2) of the liquid coolant distribution trough 28. From the liquid coolant- receiving surface 18, the liquid coolant 27 flows downwardly towards the bottom of the evaporative pad 12. The reservoir 20 also includes a drain 23 for removing sludge from the bottom portion of the reservoir that may accumulate over time.

The liquid coolant 27 distributed to the liquid coolant-receiving surface 18 and passing into the evaporative pad 12 wets the evaporator pad as the liquid coolant flows downwardly through the pad and, thereby, the liquid coolant tends to be retained, at least in part, at the evaporator pad. To the extent that the liquid coolant 27 is not retained at the evaporative pad 12, the liquid coolant will flow from the evaporator pad at a liquid coolant-exiting surface 19 that is included as a part of the evaporator pad. Thus, the liquid coolant 27, water in the presented example, which passes entirely through the evaporative pad 12 exits the evaporative pad at the liquid coolant-exiting surface 19.

Based on the foregoing description, it will be understood that the air-entry surface 14, the air-exiting surface 16, the liquid coolant-receiving surface 18 and the liquid coolant-exiting surface 19 of the evaporative pad 12 are arranged so that air flowing from the air-entry surface 14 to the air-exiting surface 16 through the evaporative pad 12 and liquid flowing from the liquid coolant-receiving surface 18 towards the liquid coolant-exiting surface 19 through the evaporative pad come into contact with one another. As a result of this contact of the air and the liquid coolant 27, the liquid coolant evaporates so that the air flowing from the air-entry surface 14 to the air-exiting surface 16 through the evaporative pad is cooled.

The evaporative pad 12 can be made of any one of a number of evaporative cooling media. One example of a medium that can be used is plastic fibers. Corrugated structures, including structures made of corrugated cellulose or plastics also can be used. It can be important that, whatever medium is used, a large surface area be presented to the coolant and the air flowing through the evaporative pad so that cooling of the air upon contact with the liquid coolant is carried out efficiently. It also can be important that the evaporative cooling medium employed have the properties of providing for the relatively even distribution and good retention of the coolant at the medium.

Turning to a discussion of the construction of the liquid coolant distribution trough 28, as best illustrated in FIGS. 2 and 3, the example liquid coolant distribution trough can take the form of a trough that has sloping sides 29 that extend down from an open top 30 and that are inclined toward one another in the direction of the bottom of the trough. It will be understood to those skilled in the art that the sides of the trough need not be sloping as shown in the drawings but can be arranged so as to be positioned substantially vertically. The liquid coolant distribution trough 28 includes an open, upper portion 32, adjacent to/extending from the open top 30, and a lower portion 34. The open top 30 is open to the liquid-delivery header 26. Thus, the open top 30 is opposing to the liquid-delivery header 26. Recall that the liquid-delivery header 26 can be configured so as to deliver the liquid coolant in relatively equal amounts along the length L and across the width W of the trough 28. As such the liquid-delivery header 26 can be configured so as to deliver the liquid coolant in relatively equal amounts along the length L and across the width W of the open top 30 of the trough 28.

The upper portion 32 of the liquid coolant distribution trough 28 can be constructed of sheet material such as stainless steel or plastic sheeting for example and be configured to hold the liquid coolant so that the coolant cannot flow outwardly at the first portion of the liquid coolant distribution trough and can flow only downwardly in the trough. The lower portion 34 of the liquid coolant distribution trough 28 is contiguous with the upper portion 32 and includes a lower opening 36 at the base of the lower portion. Within the shown example, the opening 36 has dimensions W and L.

The lower portion 34 also includes a fabric distribution layer 37 (FIG. 2) that is supported in place within the trough 28 over the lower opening 36. It should be appreciated that the fabric distribution layer is schematically/generically shown as an example within the figures. The appearance of the fabric distribution layer 37 can be varied from the example shown within the figures. The liquid coolant 27 (FIG. 3) temporarily held in the upper portion 32 of the liquid coolant distribution trough passes through the opening 36 and the fabric distribution layer 37 and is distributed to the liquid coolant-receiving surface 18 (FIG. 2) of the evaporative pad 12. As such, the fabric distribution layer 37 is permeable. With regard to the liquid coolant 27 (FIG. 3) temporarily held within the upper portion 32 it is to be appreciated that although the fabric distribution layer 37 is permeable, a certain about of resistance to permeation is provided by the fabric distribution layer 37. As such, the entity of the fabric distribution layer 37 has at least some liquid coolant located there-above. Accordingly, the entity of the fabric distribution layer 37 is wet as the liquid coolant passes therethrough. In view of the action of liquid coolant passing through the fabric distribution layer 37, the distribution of liquid coolant exiting the bottom of the fabric distribution layer 37 and through the lower opening 36 is uniformly distributed across the entire width W and length L of the fabric distribution layer and thus the entire width W and length L of the lower opening 36. As such, it should be appreciated that the trough 28 with the fabric distribution layer 37 is not a pipe. It should further be appreciated that the trough 28 with the fabric distribution layer 37 is not a conduit pipe with a series of spray or drip nozzles thereon. Such a pipe with a series of spray or drip nozzles thereon does not provide the thorough wetting as provided by the trough 28 with the fabric distribution layer 37 in accordance with an aspect of the present invention. As mentioned, in previous designs, conduit pipes that drip or spray coolant provide uneven distribution of coolant.

In the shown example, the fabric distribution layer 37 is generally horizontally extending along its length L and across its width W, and as such liquid coolant held in the upper portion 32 of the liquid coolant distribution trough 28 is free to migrate as needed within the upper portion of the trough. Within some specific examples, an upper surface of the fabric distribution layer 37 is a flat surface. Such again provides for liquid coolant held in the upper portion 32 of the liquid coolant distribution trough 28 to be free to migrate as needed within the upper portion of the trough.

In the example illustrated in FIGS. 1 and 2, the liquid coolant distribution trough 28 is shown as supported somewhat above the liquid coolant-receiving surface 18 of the evaporative pad 12. However, the liquid coolant distribution trough 28 can be supported on and in contact with the liquid coolant-receiving surface 18.

The fabric distribution layer 37 is sufficiently permeable to allow liquid coolant held in the upper portion 32 of the liquid coolant distribution trough to pass through the fabric distribution layer and distributed to the liquid coolant-receiving surface 18 of the evaporative pad 12 at a selected rate that is sufficient to adequately keep the entirety of the evaporative pad wetted with the coolant so that the entirety of the air flowing through the pad comes into contact with the coolant and is cooled. One example of a material from which the fabric distribution layer can be made is fiberglass padding provided as a fabric. When fiberglass padding is employed, the padding can be placed over the opening 36 in the lower portion 34 of the liquid coolant distribution trough and held in place by the sloping sides 29, 29 of the trough. Another example of a material that can be used to form the fabric distribution layer is relatively finely divided plastic material that can be contained within suitable netting and the finely divided plastic-filled netting-, provided as a fabric and placed over the opening 36. As mentioned, the sides of the trough need not be sloping as shown in the drawings but can be arranged so as to be positioned substantially vertically. In that case, it can be necessary to provide retainers of a suitable sort to hold the fabric distribution layer in place over the opening 36.

In other examples, the material of the fabric distribution layer 37 may be synthetic fibrous media fabric. For example, the media may be spunbond fabric made from polypropylene, polyester, polyethylene, and/or NYLON fibers. As another example, the media may be melt blown fabric made from polypropylene, PBT (polybutylene terepthalate), PET (polyethylene terephthalate), Nylon, and/or polyethylene fibers. As another example, the media maybe hydroentangled fabrics made from polypropylene, polyester, PVDF, and/or PTFE fibers. As another example, the media may be airlaid calendared fabrics made from polypropylene, polyester, PVDF (polyvinylidene fluoride), and/or PTFE (polytetrafluoroethylene) fibers. As another example, the media may be wet laid fabrics made from microfiber glass and/or polyester fibers. For such media, the fibers can be mono-component (i.e., having two different materials in same fiber) or bi-component (i.e., having two different materials in same fiber). Also, multiple types and/or multiple techniques may be utilized. Further, the media can also have multiple layers and the multiple layers can be bonded together, such as by either thermal or adhesive lamination. The multiple layers may be the same or different. If the multiple layers are different, each layer may provide a different property and/or characteristic. See FIG. 4 for one example that has multiple layers. It should be noted that the example drawings are generic/schematic. As such, the multiple layers, the media therein, etc. can have a different appearance, arrangement, etc.

As mentioned, the liquid coolant passes through the fabric distribution layer 37. Accordingly, the fabric distribution layer has porosity. In some examples, there exists a uniform pore size across the entire length L and width W of the media. However, it is contemplated that non-uniform pore sizes can be provided. Pore size can be chosen based upon one or more criteria. In one example, the criteria is selected to optimize one or more characteristics concerning the liquid coolant passing through the fabric distribution layer 37. Some example criterion include: providing sufficient back pressure for enabling good liquid distribution, allowing sufficient liquid flow with minimal liquid head (e.g., delivering 1.5 to 2.0 gallons/min/ft² or approx. 0.5 to 0.7 liters/min/m² of liquid flow with less than 2 inches or approx. 5 cm of liquid head), and resisting pore fouling by trace quantity of contaminants present in the liquid coolant (e.g., contaminants present in water).

Further, other features and/or characteristics can be provided or utilized for the media. For example, hydrophilic or wicking treatment can be applied to enable good liquid (e.g., water) flow. As another example, the media can also be selected for mechanically durable enough to withstand continuous use for several years. As a still further example, the media can also be selected or treated for resist against mildew, mold, etc.

As mentioned, pore size can be chosen based upon one or more criteria. Also as mentioned, the media can also have multiple layers. In some examples, the pore sizes of different layers may be different. In some further examples, the layers and pores therein may provide for a gradient (e.g., progressive change) of pore sizes through media layers. Alternatively, if multiple layers are not utilized, a gradient structure of pore sizes in the distribution media could still be provided. The gradient structure of pore sizes may have various configurations. In one example, finer pores are at the liquid coolant entrance (e.g., upper) side. It is to be recalled that the fabric distribution layer 37 and the media thereof is generically/schematically shown within the figures. As such, the drawings are to be taken as representing the various possible examples of the fabric distribution layer 37 and the media thereof.

Also, the media or some layers thereof may be membrane(s). See FIG. 5 for one example that generically/schematically shows a layer that is a membrane. The shown example presented the membrane at an upper layer location. However, the membrane could be located at a lower layer location or an intermediate layer location. Examples of membranes that can be used are expanded PTFE, microporous polypropylene or polyethylene, or cast membranes such as Polyether sulfone, Nylon, PVDF. Some membranes may not be strong enough to be used as stand-alone layer. For such membranes of lesser strength, the membrane layer can be attached, such as by lamination, to a fibrous strength-providing layer. Any of the above mentioned fibrous layers can be used as a strength-providing layer. If lamination is utilized, such lamination can be done via either thermal or adhesive means. In the case of hydrophobic membrane (e.g., expanded PTFE), the membrane can be prewetted with Isopropyl alcohol or it could have a permanent hydrophilie treatment applied on it. As an example, such treatment could be Polyvinyl alcohol (PVA).

In order to be most assured that the liquid coolant distribution trough 28 will function to wet the entirety of the evaporative pad 12, as best seen in FIG. 2, the perimeter of the outer boundary of the evaporative pad 12, the perimeter of the liquid coolant-receiving surface 18 and the perimeter of the opening 36 in the lower portion 34 of the liquid coolant distribution trough 28 can be co-extensive with one another. That is, these elements can have the essentially the same outer dimensions or limits. Within the one example, the dimensions are width W by length L. As such the size of the opening 36 is congruent with the size of the liquid coolant-receiving surface 18 of the evaporative pad 12. Consequently, coolant flowing through the opening 36 in the liquid coolant distribution trough 28 will flow to the entirety of the liquid coolant-receiving surface 18 of the evaporative pad 12; and the liquid coolant passing through the liquid coolant-receiving surface 18 and into the evaporative pad 12 will flow downwardly and wet the entirety of the evaporative pad 12 so that the entirety of the air flowing through the evaporative pad will come into contact with the liquid coolant and the entirety of the flowing air cooled. Thereby, the development of hot spots in the evaporative pad 12 that can be the cause of damage to the blades of the compressor and the consequent operational failure of the gas turbine system can be avoided.

The entirety of the evaporative pad can be considered to have been wetted and the entirety of the air can be considered to have been contacted by the coolant so that the entirety of the air is cooled whenever the properties of the air passing through the evaporative pad are only negligibly different from the properties of air that has passed through the evaporator pad when it has been wetted in its entirety.

Another aspect of the invention that can be included in the construct of the liquid coolant distribution trough 28 concerns features of the liquid coolant distribution trough that result in the liquid coolant being distributed to the liquid coolant-receiving surface 18 of the evaporative pad 12 at a selected rate. The selected rate would be sufficient to cause the entirety of the evaporative pad to be wetted by the liquid coolant flowing from the liquid coolant-receiving surface 18 of the evaporator pad towards the liquid coolant-exiting surface 19 of the evaporator pad. However, the selected rate would not be substantially greater than is required for that purpose and would be insufficient to cause an excessive amount of the liquid coolant to exit the liquid coolant-exiting surface 19 of the evaporative pad 12. In this aspect, the excessive recirculation of the liquid coolant from the reservoir 20 to the liquid-delivery header 26 is avoided.

The rate at which liquid coolant will flow through the opening 36 in the liquid coolant distribution-trough 28, aside from the physical properties of the liquid coolant itself such as its viscosity for example, is dependent on the depth of the liquid coolant in the trough, or the magnitude of the head of the liquid coolant in the trough, and the permeability characteristic of the fabric distribution layer 37. Consequently, in the example of the invention shown in the drawings, the upper portion 32 of the liquid coolant distribution trough 28 is configured to maintain the liquid coolant at a selected depth in the upper portion 32 of the liquid coolant distribution trough 28 above the fabric distribution layer 37 and the fabric distribution layer has a permeability characteristic, such that the liquid coolant is distributed to the liquid coolant-receiving surface 18 of the evaporative pad 12 through the fabric distribution layer 37 at a rate that is sufficient to cause the entirety of the evaporative pad 12 to be wetted by the liquid coolant flowing from the liquid coolant-receiving surface 18 of the evaporator pad towards the liquid coolant-exiting surface 19 of the evaporator pad but insufficient to cause an excessive amount of liquid coolant to exit the liquid coolant-exiting surface of the evaporative pad.

The depth of the liquid coolant in the liquid coolant distribution trough can be controlled, simply, by controlling the height to which the top of the trough extends. In that case, coolant delivered to the trough would be delivered at a rate such that coolant would continually flow to outside the trough over the top of the trough. In the embodiment shown in the drawings, however, an alternate technique is employed to control the depth of the liquid coolant. Thus, as best seen in FIGS. 2 and 3, a notch 31 is provided in the rear panel 33 of the liquid coolant distribution trough 28. The bottom of the notch establishes the height to which coolant in the trough can be maintained, with the coolant being delivered to the trough from the liquid-delivery header 26 at a sufficient rate to cause coolant to continually, but somewhat slowly, flow through the notch in order to maintain that height. The coolant flowing from the liquid coolant distribution trough through the notch 31 can be collected and routed through a conduit, for example, to the reservoir 20. It will be understood to those skilled in the art that liquid coolant can be delivered to the liquid coolant distribution trough 28 using other than the liquid-delivery header 26 illustrated in FIG. 1. For example, a simple liquid coolant delivery line can be hung over the top of one of the sloping sides 29 of the liquid coolant distribution trough. Alternately, an opening can be made in a side of the upper portion 32 of the trough and the liquid coolant line secured to the opening at the liquid line's discharge point.

The permeability characteristic of the fabric distribution layer 37 can be established in any one or more of a number of ways. For example, the medium selected to make up the fabric distribution layer can influence the permeability characteristic of the bed. Thus, a fabric distribution layer of a fiberglass material can have a permeability characteristic that is different than the permeability characteristic of granulated material such as finely divided plastic spheres. Also, the permeability characteristic of the fiberglass material itself can be influenced by the density of the fiberglass material. As well, the permeability characteristic of the granulated material can be influenced by how tightly the granules are packed together for example.

It will be understood from the foregoing description that in one aspect, the invention can include a method of cooling air including passing a liquid coolant through an evaporative pad of an evaporative cooler and wetting the entirety of the evaporative pad with the liquid coolant as the liquid coolant passes through the evaporative pad. The method can also include passing the air to be cooled through the entirely wetted evaporative pad and contacting the entirety of the air with the entirely wetted evaporative pad, whereby the entirety of the air passing through the entirely wetted evaporative pad is cooled. In another aspect, the method can include distributing the liquid coolant to a liquid coolant-receiving surface at the evaporative pad by passing the liquid coolant through a fabric distribution layer before passing the liquid coolant into the evaporative pad. In still another aspect, the method can include maintaining the depth of the liquid coolant in the upper portion of a liquid coolant distribution trough at a level and the permeability characteristic of the fabric distribution layer at a value such that the liquid coolant is distributed to the liquid coolant-receiving surface of the evaporative pad through an opening in the liquid coolant distribution trough and the fabric distribution layer that overlies the opening at a rate that is sufficient to cause the entirety of the evaporative pad to be wetted by the liquid coolant flowing from the liquid coolant-receiving surface of the evaporator pad towards a liquid coolant-exiting surface of the evaporator pad but insufficient to cause an excessive amount of liquid coolant to exit from the liquid coolant-exiting surface of the evaporative pad. In yet further aspects, the invention can include the foregoing methods wherein liquid coolant distribution troughs and evaporative pads of the types described above can be employed and the methods are employed to provide cooled air to a gas turbine system.

While the present invention has been described above and illustrated with reference to certain embodiments thereof, it is to be understood that the invention is not so limited. Thus, the present invention has applications to evaporative cooler systems, or evaporative coolers of essentially any type. These include, but are not limited to, evaporative coolers for cooling air for thermal comfort and evaporative coolers for controlling the temperature of the air in structures such as greenhouses and buildings containing livestock.

Modifications and alterations will occur to those skilled in the art upon reading and understanding the specification, including the drawings. In any event, the present invention covers and includes any and all modifications and variations to the described embodiments that are encompassed by the following claims. 

What is claimed is:
 1. An evaporative cooler including: an evaporative pad, including a liquid coolant-receiving surface at which a liquid coolant distributed to the evaporative pad is received and thereafter passes into the evaporative pad; a liquid coolant delivery member located above the evaporative pad for delivering the liquid coolant to a location above the evaporative pad; and a liquid coolant distribution trough for receiving the liquid coolant that is delivered to the location above the evaporative pad and for distributing the liquid coolant to the liquid coolant-receiving surface of the evaporative pad, the liquid coolant distribution trough including an upper portion for receiving the liquid coolant and temporarily holding the liquid coolant and a lower portion contiguous with the upper portion, the lower portion including an opening directed to the liquid coolant-receiving surface of the evaporative pad and sized congruently with a size of the liquid coolant-receiving surface of the evaporative pad, and the lower portion including a fabric distribution layer in place over the opening through which the liquid coolant temporarily held in the upper portion of the liquid coolant distribution trough passes and is distributed to the liquid coolant-receiving surface of the evaporative pad, the liquid coolant temporarily held in the upper portion of the liquid coolant distribution trough wetting an entirety of the fabric distribution layer and the liquid coolant passing through the fabric distribution layer wetting an entirety of the liquid coolant-receiving surface of the evaporative pad.
 2. The evaporative cooler of claim 1, wherein a perimeter of an outer boundary of the evaporative pad, a perimeter of the liquid coolant-receiving surface and a perimeter of the opening in the lower portion of the liquid coolant distribution trough have a shared boundary.
 3. The evaporative cooler of claim 1, wherein the upper portion of the liquid coolant distribution trough is configured to maintain the temporarily held liquid coolant at a selected depth in the upper portion of the liquid distribution trough above the fabric distribution layer, and the fabric distribution layer has a permeability characteristic such that the liquid coolant is distributed to the liquid coolant-receiving surface of the evaporative pad through the fabric distribution layer to cause the evaporative pad to be wetted by the liquid coolant flowing from the liquid coolant-receiving surface of the evaporator pad towards the liquid coolant-exiting surface of the evaporator pad but insufficient to cause liquid coolant to exit the liquid coolant-exiting surface of the evaporative pad.
 4. The evaporative cooler of claim 1, wherein the fabric distribution layer includes a flat upper surface to allow horizontal movement of the temporarily held liquid coolant in the upper portion of the trough.
 5. The evaporative cooler of claim 1, wherein the fabric distribution layer is porous and has pores.
 6. The evaporative cooler of claim 5, wherein the pores are of uniform size.
 7. The evaporative cooler of claim 5, wherein the pores are of a size sufficient provide a back pressure for enabling the liquid coolant to be temporarily held within the upper portion of the trough.
 8. The evaporative cooler of claim 7, wherein the pores are of a size to provide 1.5 to 2.0 gallons/min/ft2 of liquid coolant flow with less than 2 inches of liquid coolant head.
 9. The evaporative cooler of claim 5, wherein the fabric distribution layer has at least one of a hydrophilic treatment and a wicking treatment.
 10. The evaporative cooler of claim 1, wherein the fabric distribution layer includes a spunbond fabric.
 11. The evaporative cooler of claim 10, wherein the spunbond fabric includes at least one of polypropylene, polyester, polyethylene, and Nylon.
 12. The evaporative cooler of claim 1, wherein the fabric distribution layer includes a melt blown fabric.
 13. The evaporative cooler of claim 12, wherein the melt blown fabric includes at least one of polypropylene, PBT, PET, Nylon and polyethylene.
 14. The evaporative cooler of claim 1, wherein the fabric distribution layer includes a needlepunched fabric.
 15. The evaporative cooler of claim 14, wherein the needlepunched fabric includes at least one of polypropylene, polyester, PVDF and PTFE.
 16. The evaporative cooler of claim 1, wherein the fabric distribution layer includes a hydroentangled fabric.
 17. The evaporative cooler of claim 16, wherein the hydroentangled fabric includes at least one of polypropylene, polyester, PVDF and PTFE.
 18. The evaporative cooler of claim 1, wherein the fabric distribution layer includes an airlaid calendared fabric.
 19. The evaporative cooler of claim 1, wherein the fabric distribution layer includes a membrane.
 20. The evaporative cooler of claim 1, wherein the fabric distribution layer includes multiple layers, with at least two of the multiple layers having differing materials. 